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// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#pragma once
#ifndef __Fuchsia__
#error Fuchsia-only Header
#include <utility>
#include <blobfs/transaction-manager.h>
#include <blobfs/write-txn.h>
#include <fbl/function.h>
#include <fbl/intrusive_single_list.h>
#include <fs/vfs.h>
namespace blobfs {
// A wrapper around a WriteTxn with added support for callback invocation on completion.
class WritebackWork : public WriteTxn,
public fbl::SinglyLinkedListable<std::unique_ptr<WritebackWork>> {
using ReadyCallback = fbl::Function<bool()>;
using SyncCallback = fs::Vnode::SyncCallback;
WritebackWork(TransactionManager* transaction_manager);
virtual ~WritebackWork() = default;
// Sets the WritebackWork to a completed state. |status| should indicate whether the work was
// completed successfully.
void MarkCompleted(zx_status_t status);
// Returns true if the WritebackWork is "ready" to be processed. This is always true unless a
// "ready callback" exists, in which case that callback determines the state of readiness. Once
// a positive response is received, the ready callback is destroyed - the WritebackWork will
// always be ready from this point forward.
bool IsReady();
// Adds a callback to the WritebackWork to be called before the WritebackWork is completed,
// to ensure that it's ready for writeback.
// Only one ready callback may be set for each WritebackWork unit.
void SetReadyCallback(ReadyCallback callback);
// Adds a callback to the WritebackWork, such that it will be signalled when the WritebackWork
// is flushed to disk. If no callback is set, nothing will get signalled.
// Multiple callbacks may be set. They are invoked in "first-in, last-out" order (i.e.,
// enqueueing A, B, C will invoke C, B, A).
void SetSyncCallback(SyncCallback callback);
// Persists the enqueued work to disk,
// and resets the WritebackWork to its initial state.
zx_status_t Complete();
// Optional callbacks.
ReadyCallback ready_cb_; // Call to check whether work is ready to be processed.
SyncCallback sync_cb_; // Call after work has been completely flushed.
} // namespace blobfs